A helicopter crash-landed on top of a 51-storey building in New York City on Monday, catching fire and killing the pilot.
The helicopter took off at 1:32pm from the heliport on 34th Street, and flew for 11 minutes before crashing.
The pilot was named by local media on Monday night as Tim McCormack, and he had been flying a private client shortly before the accident.
He had finished the trip, and was heading home to Linden, New Jersey, when the crash happened.
The helicopter was reportedly owned by a company called American Continental Properties Inc, the New York Post said.
Bill de Blasio, the mayor of New York, said it was "a very unusual situation".
He added: "Helicopters have not been landing on New York buildings for decades. The helicopter should not have been in this area."
Mr de Blasio said "a horrible incident" had been avoided, given that the helicopter was "obliterated", but very little debris hit the ground.
He said the pilot was an experienced commercial pilot, and they had no idea yet what caused the crash.
The fire was extinguished rapidly by the city’s fire fighters.
The Federal Aviation Authority (FAA) said they believe the pilot was the only passenger on board. They said the helicopter was an Augusta A109E.
Andrew Cuomo, the governor of New York, said it appeared that the helicopter pilot made an emergency landing. The city was doused in heavy rain on Monday, with thick clouds causing delays of 90 minutes at the major airports.
"If you are a New Yorker you have a level of PTSD from 9/11,” said Mr Cuomo. “That's immediately where your mind goes.
“But there is no indication at the moment of anything more than that. This is only preliminary, and it evolves all the time, but that's what we know."
Nicolas Estevez was standing across the street from the building when a 30 cm piece of metal that appeared to be from the helicopter landed on the pavement just feet away.
The crash, which sent people streaming out of the building within seconds, reminded him of September 11, Estevez said.
"I saw the explosion and the smoke coming out," he said.
Donald Trump tweeted his admiration of the emergency services, saying they did a "phenomenal job", and saying the federal administration was ready to help in any way.
I have been briefed on the helicopter crash in New York City. Phenomenal job by our GREAT First Responders who are currently on the scene. THANK YOU for all you do 24/7/365! The Trump Administration stands ready should you need anything at all.— Donald J. Trump (@realDonaldTrump) June 10, 2019
It remained unclear why the helicopter was in the air. Helicopter sightseeing tours are popular, and television and photography crews fly frequently, but the visibility was extremely limited. Executives use helicopters to arrive in and leave the city, but they usually avoid going over central Manhattan.
There was not believed to be a helicopter landing pad on the roof.
Workers inside the office building told of feeling a shaking sensation, and then being asked to evacuate. The stairwells were crowded, many said, yet people remained calm.
Morgan Aries, working inside the building on the 14th floor, said he felt a large tremor. They were told initially to stay in their seats, but after five minutes were told to leave.
"It was a little unnerving in the stairwell, as no one knew what was going on," he told CNN.
"We were all checking our phones, looking for updates. There were a lot of sirens, but we didn't see any smoke or debris."